/*
 * TouchGraph LLC. Apache-Style Software License
 *
 *
 * Copyright (c) 2002 Alexander Shapiro. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by
 *        TouchGraph LLC (http://www.touchgraph.com/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "TouchGraph" or "TouchGraph LLC" must not be used to endorse
 *    or promote products derived from this software without prior written
 *    permission.  For written permission, please contact
 *    alex@touchgraph.com
 *
 * 5. Products derived from this software may not be called "TouchGraph",
 *    nor may "TouchGraph" appear in their name, without prior written
 *    permission of alex@touchgraph.com.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL TOUCHGRAPH OR ITS CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 */

package geovista.touchgraph.interaction;

import java.awt.Point;
import java.awt.event.MouseEvent;

import geovista.touchgraph.Node;
import geovista.touchgraph.TGPanel;

/**
 * DragNodeUI contains code for dragging nodes.
 * 
 * <p>
 * <b> Parts of this code build upon Sun's Graph Layout example.
 * http://java.sun.com/applets/jdk/1.1/demo/GraphLayout/Graph.java </b>
 * </p>
 * 
 * @author Alexander Shapiro
 * 
 */
public class DragNodeUI extends TGAbstractDragUI {

	/**
	 * Stores the distance between the cursor and the center of the node when
	 * dragging occurs so that the cursor remains at the same position on the
	 * node otherwise, the cursor jumps to the center of the node.
	 */
	public transient Point dragOffs;

	// ............

	/**
	 * Constructor with TGPanel <tt>tgp</tt>.
	 */
	public DragNodeUI(TGPanel tgp) {
		super(tgp);
	}

	@Override
	public void preActivate() {
		if (dragOffs == null) {
			dragOffs = new Point(0, 0);
		}
	}

	@Override
	public void preDeactivate() {
	}

	@Override
	public void mousePressed(MouseEvent e) {
		Node mouseOverN = tgPanel.getMouseOverN();
		Point mousePos;

		if (e != null) {
			mousePos = e.getPoint(); // e can be null if the wrong activate()
										// method was used
		} else {
			mousePos = new Point((int) mouseOverN.drawx, (int) mouseOverN.drawy);
		}

		if (mouseOverN != null) { // Should never be null if TGUIManager works
									// properly
			tgPanel.setDragNode(mouseOverN);

			dragOffs.setLocation((int) (mouseOverN.drawx - mousePos.x), // For
																		// when
																		// you
																		// click
																		// to
																		// the
																		// side
																		// of
					(int) (mouseOverN.drawy - mousePos.y));// the node, but you
															// still want to
															// drag it
		}
	}

	@Override
	public void mouseReleased(MouseEvent e) {
		tgPanel.setDragNode(null);
		tgPanel.repaintAfterMove();
		tgPanel.startDamper();
	}

	@Override
	public void mouseDragged(MouseEvent e) {
		Node dragNode = tgPanel.getDragNode();
		dragNode.drawx = e.getX() + dragOffs.x;
		dragNode.drawy = e.getY() + dragOffs.y;
		tgPanel.updatePosFromDraw(dragNode);
		tgPanel.repaintAfterMove();
		tgPanel.stopDamper(); // Keep the graph alive while dragging.
	}

} // end com.touchgraph.graphlayout.interaction.DragNodeUI
